Shear knife positioning apparatus



June 16, 1964 J. w. O'BRIEN 3,137,191

SHEAR KNIFE POSITIONING APPARATUS Filed Aug. 29, 1960 3 Sheets-Sheet 1 FIG. 1

INVENTOR. MIAH w O'BRIEN O B HIS ATTORNEY FIG. 2 1E June 16, 1954 w, O'BRIEN 3,137,191

SHEAR KNIFE POSITIONING APPARATUS Filed Aug. 29, 1960 3 Sheets-Sheet 2 Y 3 INVENTOR.

JEREMIAH w. O'BRIEN j= Q WM;

' HIS A TORN-E'Y June 16, 1964 J. w. O'BRIEN 3,137,191

SHEAR KNIFE POSITIONING APPARATUS Filed Aug. 29, 1960 3 Sheets-Sheet 3 FIG 8 END OF our United States Patent This invention relates to a shear having two movable knives, and particularly to meansfor automatically positioning one of the knife heads relative to the material to be cut. While the positioning means is adapted to be successfully employed with other types of shears, for the purpose of description, it will be explained in combination with a down-and-up cut shear.

The most desirable action for a down-andup cut type shear is to have the top knife head come down and gently stop within a short distance from the material, while the lower knife head rises and makes the cut. tendency of the shear, due to inherent mechanical design, is for the top head to descend and strike the material, bringing the head suddenly to a stop, developing shock to the shear mechanism and hydraulic system, as Well as a damaging blow to the table rollers.

One method to control the motion of the top knife head has been with pre-set flow control valves in the hydraulic balance system. The adjustment of thesevalves is very critical, and one setting is not adequate for a wide range of material thickness.

The present invention has been devised to control automatically the stopping of the top head a desirable distance above the material for any thickness range within the capacity of the shear. The mechanism, in one form, utilizes the existing hydraulic gag linkage, although separate means can also be provided if convenience of design would warrant it. Also, while in the preferred form, parts of the control are cooperatively associated with the top head of the shear, this construction need not prevail in all cases and still the advantages ofthe present invention can be realized. The major purpose of the gag is to clamp the material to the lower knife head to effect an improved cut and to strip it from the top head after the shearing action is over should the sheared portion adhere thereto.

According to the present invention, in a construction where the control is associated directly with the top shear head, the gag or other equivalent means serves as a feeler and is first dropped to a position in which its lower surface is a predetermiend distance below the edge of the upper knife blade. Thereafter the entire upper knife head is dropped as a unit. During this movement, the gag engages the material first, and because the rest of the upper knife head continues to descend, there results movement of the upper knife head relative to the gag. This relative movement is used to control flow from the hydraulic balance cylinders to stop the upper knife head The Prior Art One form of the present invention is an improvement However, the

ice

in the type of shear disclosed in US. Patent No. 2,043,398 toSmitmans.

In the Smitmans patent the upper knife head and the lower knife head are guided for vertical movement toward and away from each other in a shearing action.

A drive shaft, which is connected by flexible couplings to a source of power, is journaled in the lower knife head and drives a pair of eccentrics. These eccentrics rotate in bearings in the lower ends of connecting rods which have their upper ends pivotally attached to the upper knife head. Since the assembly, which includes both knife heads, is biased downwardly by gravity, the first part of the rotation of the eccentrics moves the upper knife head down into contact with the bloom. Further rotation causes the eccentrics to pull down on the connecting rods, but since these rods cannot move downwardly (because the upper knife head is in contact with the bloom. This part of the rotation of the eccentrics reacts upwardly and causes the lower knife head to move upwardly in a cutting blow which severs the bloom.

Counterweights are used to partly balance the Weight of the upper and lower knife heads.

This type of shear is used especially in the steel industry to shear blooms, billets, slabs, bars, etc., either hot 01 cold. For convenience of description the term bloom will be used to designate the material to be sheared.

In order to form a background for understanding the present invention as applied to a down-and-upcut shear, the salient features of this embodiment will now be described.

The frame It is provided with a pair of guideways 11 in which the upper knife head 12 is guided for vertical movement. The upper knife head is itself provided with a pair of guideways 13 in which the lower knife head 14 is guided for vertical movement. A cutting knife 15 is bolted to the upper knife head and a similar cutting knife 16 is bolted to the lower knife head (FIG. 3).

The shearing action of the knife heads is caused by cam action of the parts now to be described.

The main drive shaft 17 is journaled in bearings in the lower end of the lower knife head 14. Just outside the lower knife head and on each side, the drive shaft 17 carries eccentrics 18. The drive end 19 of the shaft 17 carries a coupling member Ztlwhich is part of a flexible main shaft. A flexible main shaft is necessary to permit upward movement of the drive shaft 17 in a manner 'presently to be explained.

An upper squeeze shaft 21 is journaled in the upper knife head 12 and has ends which project outwardly beyond the knife head. To each of these projecting ends is attached a pressure link 22 which carries at its lower extremity a big end 23 journaled on one of the eccentrics 18.

The shearing aciton of the knife heads is similar to that summarized above in connection with the Smitmans patent. During the first part of the rotation of the main drive shaft 17, the upper knife head descends (because the assembly of upperand lower knife heads is biased downwardly by gravity). Further rotation of the eccentrics 18 causes them to pull down on the pressure links 22, but as the squeeze shaft '21 is now held in fixed position relative to the bloom, this motion forces the lower knife head upwardly to make the shearing cut. Thus it is seen that the eccentrics serve as crank means for closing the knives.

Instead of the counterweights shown in the Smitmans patent, this embodiment uses hydraulic balancing cylinders to partially balance the weight of the knife heads. A cylinder 24 at each side of the upper knife head, and cylinders 25 at each side of the lower knife head, perform this function.

This commercial embodiment also is provided with a gag element which is pressed by hydraulic pressure into contact with the bloom.

The gag 26 (FIGS. 2 and 3) has a pressure foot 27, and is guided for vertical movement in guideways 28 formed in the lower knife head. Upward movement of the gag is cushioned by hydraulic cylinder 29 and its associated parts.

A main gag lever 30 is pivoted intermediate its ends on a shaft 31 carried on the upper knife head. One end of the lever 30 is pivotally connected to the push rod 32 of the cylinder 29. In the commercial embodiment referred to, the upper end of gag 26 is pivotally connected to the opposite end of the main gag lever 30. In this form the gag is caused to engage the bloom as the bloom is pushed up against the upper knife blade to thus clamp the material to the lower knife head, which clamping action improves the shape of the cut and serves to strip it from the top knife head after the shearing action is over.

However, in this form the gag is not used to accurately pre-position the upper knife head relative to the bloom, which is the purpose of the present invention.

The Present Invention According to the present invention the gag 26 is used as a feeler to make preliminary contact with the bloom, and to actuate control mechanism which automatically brings the upper knife head to a pro-determined distance from the bloom. This is accomplished for varying thicknesses of bloom, within the tolerance of the device, in a manner which will now be explained.

An auxiliary gag lever 33, which is a lever of the third class, has one end fulcrumed about the same axis as shaft 31. Its opposite end is connected to the upper end of gag 26 by means of a pivot link 34.

An auxiliary hydraulic gag cylinder 35 is pivoted at 36 on the lever 30, and the lower end of its pull rod 37 is pivoted at 38 to lever 33. It is seen that vertical reciprocation of the pull rod 37 will rock the auxiliary gag lever 33 about the pivot 31, and thus reciprocate the gag 26 vertically.

The end of auxiliary gag lever 33 which pivots about axis 31 is connected by linkage to a control valve 39 (FIGS. 1 and 2) which has a limited control over vertical movement of the upper knife head.

This connection includes a shaft 40 which is connected at one end by a flexible coupling 41 and a stud shaft 41a to the auxiliary gag lever 33. The opposite end of shaft 40 is connected by a flexible coupling 42 to a stud shaft 43 journaled in a bearing 44 mounted on the frace.

The outer end of stud shaft 43 carries an arm 45 the outer end of which is pivotally connected to a push rod 46 which slides vertically in a guide 47 mounted on the frame. The lower end of the push rod 46 is adapted at certain times to engage the stem 48 of the control valve 39, as will be presently explained.

Operation of the Invention The invention relates especially to the sequence of movements of the gag and the knife heads, as illustrated diagrammatically in FIGS. 4 to 8.

The bloom 49 moves over a bed of rollers 50 in the direction of the arrow in FIG. 4.

Read Position (FIG. 4

In FIG. 4 the shear is in ready or non-operating position. In this position, illustrated also in FIG. 3, the various parts are in these positions.

(a) The knife heads are in full open position.

(b) Push rod 32 of main hydraulic gag cylinder 29 is in full out position.

(0) The auxiliary gag cylinder 35 is holding the auxiliary gag lever 33 up against the main gag lever 3%).

(d) The lower surface of the gag pressure foot 27 is level with the bottom of the upper knife 15.

(e) The control valve 39 is in closed position as shown in FIG. 3. (Spring-biased to closed position.)

The bloom is now free to pass through the shear in the direction of the arrow in FIG. 4 until a cut is to be made. At this time the operator presses a button to trigger the shearing cycle.

The first thing that happens is that fluid is permitted to exhaust from the auxiliary gaf cylinder 35, thus permitting the auxiliary gag lever 33 to drop until a stop pad 51 carried by lever 33 engages a stop pad 52 mounted on the upper knife head. The dropping of the outer end of the auxiliary gag lever 33 permits the gag 26 to drop relative to the upper knife head 12 until the parts are in the position of FIG. 5.

Feeler Position (FIG. 5)

The amount of drop of the gag 26 is determined by the positions of the stop pads 51 and 52. In a particular instance this may be approximately 3 /2 in. This may be called the feeler" position, because in this position the gag extends below the level of the upper knife 15, and is ready to act as a feeler in the accurate positioning of the upper knife head.

When the auxiliary gag lever 33 dropped as just explained, it moved clockwise (as viewed in FIGS. 3, 4-8,), and caused a corresponding turning movement of control shaft 40. This turning of shaft pressed lever arm and push rod 46 downwardly into engagement with the stem of control valve 39.

This movement opened valve 39 and permitted hydraulic fluid to exhaust from the upper balance cylinders 24, thus allowing the top knife head to descend with the gag in its lowered position. The top knife head continues to descend to bring the lower surface of the gag pressure foot 27 into contact with the upper surface of the bloom. The parts are now in the position of FIG. 6.

First Contact (FIG. 6)

As explained previously, there may be considerable variation in the thickness of the bloom, but in any case, the upper knife head continues its descent as long as may be necessary to bring the parts to the first contact position of FIG. 6.

After the lower end of the gag engages the bloom, the upper knife head continues to descend. This downward movement of the knife head while the gag remains stationary causes reverse rotation (counter-clockwise) of the end of auxiliary gag lever 33 which pivots about axis 31. This action causes counter-clockwise rotation of shaft 40 and arm 45, to raise the push rod 46 to its position out of contact with the stem of control valve 39 as shown in FIG. 2.

Valve 39 is now automatically spring closed, thus stopping escape of fluid from the upper balance cylinders 24 and stopping the descent of the upper knife head in the position of FIG. 7.

Start of Cut (FIG. 7)

The parts are so proportioned and adjusted that in the position of FIG. 7 the lower surface of the upper knife head is at the desired preliminary height above the bloom.

In the particular example used, where the gag was permitted to descend 3 /2 in. to the feeler position of FIG. 5, the top knife head is permitted to drop 3 in. from the first contact position of FIG. 6 to the start-of-cut position of FIG. 7. This means that the upper knife head is now /2 in. above the bloom, which is considered to be a desirable preliminary spacing.

In the continuation of the shearing action the lower knife head 14 now moves upward from the position of FIG. 7 in the shearing stroke. During the first part of this upward movement the lower knife head pushes the bloom upward, moving the gag upward, causing the stop pad 53 on the auxiliary gag lever 33 to engage the stop pad 54 on the main gag lever 30, and tilting the main gag level in a counter-clockwise direction to depress push rod 32 into hydraulic cylinder 29. In this way the gag 26 and cylinder 29 absorb the initial shock of the shearing blow.

As the lower knife 16 continues its upward movement it completes the shear, and-moves above the lower surface of the upper knife 15, pushing the gag upward still farther against the cushioning resistance of cylinder 29. The parts are now in the position of FIG. 8.

End of Cut (FIG. 8)

Functions Performed by the Gag It will be noted from the above description that in the invention the gag serves these functions: 7

(1) During the preliminary positioning it serves as a ,feeler to automatically determine the position of the top knife head.

(2) It clamps the bloom to the lower knife head during the cutting stroke.

(3) It strips the material from the top knife after the shearing action is over.

Conclusion It will be clear from the above description that in'the I present invention the gag or other means, which may be divorced from or as illustrated associates with the top shear head, is used as a feeler to position the upper knife head a desired pre-determined distance above the bloom, thus preventing this knife head from hitting the bloom during its descent, with the harmful consequences mentioned above. In addition, when the gag is used as the feeler, it serves all its useful functions as in the prior art.

According to the provisions of the patent statutes, I

have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, Within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a shear of the doWn-and-up cut type adapted to shear a bloom and which comprises:

a frame;

upper and lower knife heads mounted in the frame for opposed vertical movement and carrying cutting knives;

means for closing the knives in a shearing action where in the upper knife is brought into a cutting position and after which the lower knife is raised to effect a cut;

a bloom-engaging means mounted for vertical movement relative to the upper knife head and adjacent to the upper knife;

the bloom-engaging means being so mounted that it can project below the level of the upper knife to contact the bloom prior to contact of the upper knife with the bloom;

the upper end of the bloom-engaging means being operatively connected to a force exerting means to urge the bloom-engaging means against the bloom;

the improvement which comprises:

hydraulic means to drop the bloom-engaging means to a position in which its lower surface is a predeter- 8 mined distance below the edge of the upper knife; hydraulic means to thereafter drop the upper knife head and the bloom-engaging means together;

a throttle valve in the last-named hydraulic means;

and control linkage connecting the bloom-engaging means to the throttle valve;

said control linkage being connected to open the throttle valve to effect operation of the last-named hydraulic means when the bloom-engaging means is lowered relative to the upper knife head, and to close the throttle valve to elfect an interruption of the operation of said last-named hydraulic means when thereafter the upper knife head is lowered a predetermined distance relative to the bloom-engaging means;

whereby the lower edge of the upper knife is positioned a predetermined distance above the bloom prior to the upward cutting movement of the lower knife.

2. In a shear of the down-and-up cut type adapted to shear a bloom and which comprises:

a frame;

upper and lower knife heads mounted in the frame for opposed vertical movement and carrying knives;

eccentrics for closing the knives in a shearing action wherein the upper knife is broughtinto a cutting position and after which the lowerknife is raised to eifect a cut;

hydraulic head cylinders carried by said frame and connected to the upper knife head;

a gag mounted for vertical movement relative to the upper knife head and adjacent to the upper knife;

a main gag lever pivoted at its intermediate portion about a shaft mounted on the upper knife head;

one end of the main gag lever being in operative relation to the upper end of the gag, so that upward motion of the gag tilts the main gag lever;

a hydraulic gag cylinder mounted on the upper knife head and connected to the other end of the main gag lever to clamp the bloom between the gag and lower knife head;

an auxiliary gag lever having one end pivoted about said shaft and its other end connected to the upper end of the gag;

an auxiliary hydraulic gag cylinder mounted on the upper knife head and connected to the auxiliary gag lever, and adapted to drop the auxiliary gag lever relative to the main gag lever to position the gag with its lower surface a predetermined distance below the edge of the upper knife;

hydraulic lines connected to said hydraulic head cylinders;

a throttle valve in said hydraulic lines;

and control linkage connected to the throttle and operated by movement of the auxiliary gag lever relative to the upper knife head;

said control linkage being connected to open the throttle valve to effect operation of said hydraulic head cylinders when the gag is lowered relative to the upper knife head, and to close the throttle valve to effect an interruption of the operation of said hydraulic head cylinders when thereafter the upper knife head is lowered a predetermined distance relative to the gag;

whereby the lower edge of the upper knife is positioned a predetermined distance above the bloom prior to the upward cutting movement of the lower knife.

3. In a shear for shearing blooms which comprises:

a frame;

upper and lower knife heads mounted in the frame for opposed vertical movement and carrying cutting knives;

means for closing the knives in a shearing action wherein the upper knife is brought into a cutting position and after which the lower knife is raised to effect a cut;

a gag mounted for vertical movement;

the gag being so mounted that it can project below the level of the upper knife to contact the bloom prior to contact of the upper knife with the bloom;

the upper end of the gag being operatively connected to a hydraulic cylinder to clamp the bloom between the gag and lower knife head;

the improvement which comprises;

hydraulic means to position the gag in a first position and in a second position in which its lower surface is a predetermined distance below the edge of the upper knife;

hydraulic means to thereafter drop the upper knife head and gag together;

hydraulic control means cooperatively connected to said last-named hydraulic means for controlling the operation thereof; and 7 control linkage connecting said gag to said hydraulic control means whereby on descent of said gag and said upper knife head said gag Will engage the bloom and operate said hydraulic control means to effect an interruption of the operation of said lastnamed hydraulic means so that the lower edge of the upper knife is positioned a predetermined distance above the bloom prior to the upward cutting movement of the lower knife.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A SHEAR OF THE DOWN-AND-UP CUT TYPE ADAPTED TO SHEAR A BLOOM AND WHICH COMPRISES: A FRAME; UPPER AND LOWER KNIFE HEADS MOUNTED IN THE FRAME FOR OPPOSED VERTICAL MOVEMENT AND CARRYING CUTTING KNIVES; MEANS FOR CLOSING THE KNIVES IN A SHEARING ACTION WHEREIN THE UPPER KNIFE IS BROUGHT INTO A CUTTING POSITION AND AFTER WHICH THE LOWER KNIFE IS RAISED TO EFFECT A CUT; A BLOOM-ENGAGING MEANS MOUNTED FOR VERTICAL MOVEMENT RELATIVE TO THE UPPER KNIFE HEAD AND ADJACENT TO THE UPPER KNIFE; THE BLOOM-ENGAGING MEANS BEING SO MOUNTED THAT IT CAN PROJECT BELOW THE LEVEL OF THE UPPER KNIFE TO CONTACT THE BLOOM PRIOR TO CONTACT OF THE UPPER KNIFE WITH THE BLOOM; THE UPPER END OF THE BLOOM-ENGAGING MEANS BEING OPERATIVELY CONNECTED TO A FORCE EXERTING MEANS TO URGE THE BLOOM-ENGAGING MEANS AGAINST THE BLOOM; THE IMPROVEMENT WHICH COMPRISES: HYDRAULIC MEANS TO DROP THE BLOOM-ENGAGING MEANS TO A POSITION IN WHICH ITS LOWER SURFACE IS A PREDETERMINED DISTANCE BELOW THE EDGE OF THE UPPER KNIFE; 